Tar sands deposits are found throughout the world, with large deposits being located in Venezuela and Alberta, Canada. The estimated reserves of petroleum oil in these deposits is believed to be account for 66% of the world supply, with the Venezuelan Orinoco tar sands deposit containing an estimated 1.8 trillion barrels of oil, and Canada's Athabasca tar sands deposit in Alberta containing an estimated 1.75 trillion barrels.
While conventional crude oil can be typically pumped from under the ground or flow naturally, tar sands must be mined or heated in-situ in order to recover the hydrocarbons. It is estimated that 80% of the Alberta oil sands are too far below the surface for open pit mining, so other techniques must be used to recover the oil. One such conventional in-situ mining technique is referred to as Steam-Assisted Gravity Drainage (SAGD). The process involves massive injections of steam into a deposit, where it condenses into hot water. The hot water is mixed with the tar sand to create a hydrocarbon slurry. The hydrocarbon slurry flows to a collector bore at the base of the zone, from which it is pumped to the surface and then piped to an extraction plant, where it is agitated and the oil is skimmed from the top. Major disadvantages of this process include the need for extensive water supplies and abundant energy (natural gas) to boil the water, as well as significant wastewater disposal problems.
Accordingly, it is an object of the present invention to provide a method for recovering the oil in tar sand deposits that doesn't have the disadvantages of the SAGD technique described above.